Усилители для наушников — Lehmann Audio Linear

The Linear is a headphone amplifier with preamplifier functions from the German company Lehmannaudio and has been in production since 2004. Lehmann aims it at demanding users including broadcasters, audiophile record labels and headphone makers, and it can also feed active speakers or a power amplifier. The faceplate comes in silver aluminium, black aluminium or chrome.

Key specs that matter

Output power is 400 mW into 60 ohm and 200 mW into 300 ohm. Distortion stays below 0.001 percent at 6 mW into 300 ohm, and noise sits more than 95 dB below signal at the 0 dB gain setting. Response runs from 10 Hz at minus 0.3 dB to 35 kHz at minus 1 dB, while crosstalk between channels stays under minus 70 dB at 10 kHz. Input impedance is 47 kohm. Output impedance is 5 ohm at the headphone sockets and 50 ohm at the pre-out. Gain can be set to 0, 10, 18 or 20 dB. The case is 110 mm wide, 280 mm deep and 50 mm high, weighs 1.5 kg net and draws 10 W.

Engineering and use context

Lehmann builds a discrete Class A output stage with a high quiescent current and no global feedback, which the maker says lets it drive most headphones as well as long cable runs. Gain is chosen with DIP switches on the underside, so the level can be matched once to the headphone and source and then left alone, which keeps the volume control in a useful part of its travel. Two Neutrik jacks with gold-plated contacts sit on the front and are wired in parallel, so two listeners can use the amplifier at the same time. Inputs are gold-plated RCA sockets with Teflon insulation, and a single RCA pre-out carries the volume-controlled signal to active monitors. The power supply is internal and regulated, so no external adapter is required. Owners of the original can have it rebuilt with the Linear II mainboard, which uses Low-Z copper board technology and parts from the Linear SE, from EUR 499, with 3S device feet as a EUR 99 option.

Pairing

The low output impedance suits low-impedance dynamic headphones, while the highest gain setting and its power reserve cover high-impedance studio models. Any DAC or disc player with a fixed line output connects to the RCA inputs, and the pre-out allows a pair of powered speakers to share the same volume control on a desk.

Alternatives

The Lehmannaudio Linear II is the later version of the same headphone amplifier, keeping the same output power while raising the signal to noise figure above 100 dB at the lowest gain setting.